Ferroelectric Field Effect Transistors, Pluralities Of Ferroelectric Field Effect Transistors Arrayed In Row Lines And Column Lines, And Methods Of Forming A Plurality Of Ferroelectric Field Effect Transistors

ABSTRACT

A ferroelectric field effect transistor comprises a semiconductive channel comprising opposing sidewalls and an elevationally outermost top. A source/drain region is at opposite ends of the channel. A gate construction of the transistor comprises inner dielectric extending along the channel top and laterally along the channel sidewalls. Inner conductive material is elevationally and laterally outward of the inner dielectric and extends along the channel top and laterally along the channel sidewalls. Outer ferroelectric material is elevationally outward of the inner conductive material and extends along the channel top. Outer conductive material is elevationally outward of the outer ferroelectric material and extends along the channel. Other constructions and methods are disclosed.

TECHNICAL FIELD

Embodiments disclosed herein pertain to ferroelectric field effecttransistors, to pluralities of ferroelectric field effect transistorsarrayed in row lines and column lines, and to methods of forming aplurality of ferroelectric field effect transistors.

BACKGROUND

Memory is one type of integrated circuitry, and is used in computersystems for storing data. Memory may be fabricated in one or more arraysof individual memory cells. Memory cells may be written to, or readfrom, using digit lines (which may also be referred to as bit lines,data lines, sense lines, or data/sense lines) and access lines (whichmay also be referred to as word lines). The digit lines may conductivelyinterconnect memory cells along columns of the array, and the accesslines may conductively interconnect memory cells along rows of thearray. Each memory cell may be uniquely addressed through thecombination of a digit line and an access line.

Memory cells may be volatile or non-volatile. Non-volatile memory cellscan store data for extended periods of time including when the computeris turned off. Volatile memory dissipates and therefore requires beingrefreshed/rewritten, in many instances multiple times per second.Regardless, memory cells are configured to retain or store memory in atleast two different selectable states. In a binary system, the statesare considered as either a “0” or a “1”. In other systems, at least someindividual memory cells may be configured to store more than two levelsor states of information.

A field effect transistor is one type of electronic component that maybe used in a memory cell. These transistors comprise a pair ofconductive source/drain regions having a semiconductive channel regionthere-between. A conductive gate is adjacent the channel region andseparated there-from by a thin gate insulator. Application of a suitablevoltage to the gate allows current to flow from one of the source/drainregions to the other through the channel region. When the voltage isremoved from the gate, current is largely prevented from flowing throughthe channel region. Field-effect transistors may also include additionalstructure, for example reversibly programmable charge storage regions aspart of the gate construction. Transistors other than field-effecttransistors, for example bipolar transistors, may additionally oralternately be used in memory cells. Transistors may be used in manytypes of memory. Further, transistors may be used and formed in arraysother than memory.

One type of transistor is a ferroelectric field effect transistor(FeFET) wherein at least some portion of the gate construction comprisesferroelectric material. Such materials are characterized by two stablepolarized states. These different states in field effect transistors maybe characterized by different threshold voltage (V_(t)) for thetransistor or by different channel conductivity for a selected operatingvoltage. Polarization state of the ferroelectric material can be changedby application of suitable programming voltages, and which results inone of high channel conductance or low channel conductance. The high andlow conductance, invoked by the ferroelectric polarization state,remains after removal of the programming gate voltage (at least for atime). The status of the channel can be read by applying a small drainvoltage which does not disturb the ferroelectric polarization.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic perspective view of a portion of a substratefragment comprising a ferroelectric field effect transistor constructionin accordance with an embodiment of the invention.

FIG. 2 is a section view taken through line 2-2 in FIG. 1.

FIG. 3 is a section view taken through line 3-3 in FIG. 1.

FIG. 4 is a diagrammatic perspective view of a portion of a substratefragment comprising an array of ferroelectric field effect transistorconstructions in accordance with an embodiment of the invention.

FIG. 5 is a section view taken through line 5-5 in FIG. 4.

FIG. 6 is a section view taken through line 6-6 in FIG. 4.

FIG. 7 is a diagrammatic perspective view of a portion of a substratefragment comprising an array of ferroelectric field effect transistorconstructions in accordance with an embodiment of the invention.

FIG. 8 is a section view taken through line 8-8 in FIG. 7.

FIG. 9 is a section view taken through line 9-9 in FIG. 7.

FIG. 10 is a diagrammatic section view of a portion of a substratefragment comprising an array of ferroelectric field effect transistorconstructions in accordance with an embodiment of the invention.

FIG. 11 is a diagrammatic perspective view of a portion of a substratefragment in process in accordance with an embodiment of the invention.

FIG. 12 is a view of the FIG. 11 substrate at a processing stepsubsequent to that shown by FIG. 11.

FIG. 13 is a section view taken through line 13-13 in FIG. 12.

FIG. 14 is a section view taken through line 14-14 in FIG. 12.

FIG. 15 is a view of the FIG. 12 substrate at a processing stepsubsequent to that shown by FIG. 12.

FIG. 16 is a section view taken through line 16-16 in FIG. 15.

FIG. 17 is a section view taken through line 17-17 in FIG. 15.

FIG. 18 is a view of the FIG. 16 substrate at a processing stepsubsequent to that shown by FIG. 16.

FIG. 19 is a view of the FIG. 17 substrate at a processing stepsubsequent to that shown by FIG. 17, and corresponding in processingsequence to that of FIG. 18.

FIG. 20 is a view of the FIG. 18 substrate at a processing stepsubsequent to that shown by FIG. 18.

FIG. 21 is a view of the FIG. 19 substrate at a processing stepsubsequent to that shown by FIG. 19, and corresponding in processingsequence to that of FIG. 20.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

A ferroelectric field effect transistor 10 in accordance with anembodiment of the invention is initially described with reference toFIGS. 1-3. Example transistor 10 is shown as having been fabricatedrelative to an underlying substrate 14, which may include semiconductivematerial 12 of a semiconductor substrate. In the context of thisdocument, the term “semiconductor substrate” or “semiconductivesubstrate” is defined to mean any construction comprising semiconductivematerial, including, but not limited to, bulk semiconductive materialssuch as a semiconductive wafer (either alone or in assemblies comprisingother materials thereon), and semiconductive material layers (eitheralone or in assemblies comprising other materials). One example issemiconductor-on-insulator. The term “substrate” refers to anysupporting structure, including, but not limited to, the semiconductivesubstrates described above.

Any of the materials and/or structures described herein may behomogenous or non-homogenous, and regardless may be continuous ordiscontinuous over any material that such overlie. As used herein,“different composition” only requires those portions of two statedmaterials that may be directly against one another to be chemicallyand/or physically different, for example if such materials are nothomogenous. If the two stated materials are not directly against oneanother, “different composition” only requires that those portions ofthe two stated materials that are closest to one another be chemicallyand/or physically different if such materials are not homogenous. Inthis document, a material or structure is “directly against” anotherwhen there is at least some physical touching contact of the statedmaterials or structures relative one another. In contrast, “over”, “on”,and “against” not preceded by “directly”, encompass “directly against”as well as construction where intervening material(s) or structure(s)result(s) in no physical touching contact of the stated materials orstructures relative one another. Further, unless otherwise stated, eachmaterial may be formed using any suitable existing oryet-to-be-developed technique, with atomic layer deposition, chemicalvapor deposition, physical vapor deposition, epitaxial growth, diffusiondoping, and ion implanting being examples.

Example material 12 includes appropriately p-type and/or n-type dopedmonocrystalline or polycrystalline silicon. FIGS. 1-3 depict transistor10 in the absence of surrounding materials and circuitry for clarity.Other components of integrated circuitry may be elevationally outward,elevationally inward, and/or to the sides of transistor 10.Additionally, multiple such transistors would likely constitute part ofintegrated circuitry, for example an array of such transistors thatmight be used in memory circuitry, logic circuitry, or other circuitry.

Ferroelectric transistor 10 comprises a semiconductive channel 14 (FIGS.2 and 3) that has opposing sidewalls 16, 18 (FIG. 2), opposite ends 17(FIG. 3), and an elevationally outermost top 20 (FIGS. 2 and 3). Asource/drain region 22 (FIGS. 1 and 3) is at opposite ends 17 of channel14. Example ferroelectric transistor 10 may be p-type or n-type, andlightly doped drain regions, halo regions, etc. (not shown) may be used.Regardless, transistor 10 is shown in part as having been fabricatedrelative to a rail or fin 25 that extends elevationally from a base 26,each of which comprises semiconductive material 12. An exampleelevational projecting distance of rail 25 relative to an elevationallyoutermost surface of base 26 is about 200 to 2,000 Angstroms. An examplemaximum elevational thickness T_(SD) for source/drain regions 22 isabout 100 to 1,000 Angstroms. Regardless, FIGS. 1-3 show source/drainregions 22 only being in elevationally outmost portions of rail 25.Alternately, as examples, the source/drain regions may project deeperinto rails 25, including completely elevationally there-into orthere-through. Further, the source/drain regions may comprise elevatedsource/drain material.

Ferroelectric transistor 10 includes a gate construction 28 comprisingvarious materials. Example gate construction 28 includes innerdielectric 30 extending along channel top 20 and laterally along channelsidewalls 16, 18. Example inner dielectric materials 30 include one orboth of silicon dioxide and silicon nitride. An example thickness fordielectric 30 is about 10 to 100 Angstroms. In this document,“thickness” by itself (no preceding directional adjective) is defined asthe mean straight-line distance through a given material or regionperpendicularly from a closest surface of an immediately adjacentmaterial of different composition or of an immediately adjacent region.Additionally, the various materials described herein may be ofsubstantially constant thickness or of variable thicknesses.

Inner conductive (i.e., electrically) material 32 (designated in FIGS. 1and 3) is elevationally and laterally outward of inner dielectric 30 andextends along channel top 20 and laterally along channel sidewalls 16,18. Example inner conductive materials 32 include any suitable one ormore of elemental metals, alloys of two or more elemental metals,conductive metal compounds, and conductively doped semiconductivematerial. Example construction 28 shows inner conductive material 32 ascomprising materials 31 and 33. In one example, each may be of the samechemical composition, for example TiN formed using two differentdeposition techniques as described below in connection with a methodembodiment of the invention.

Outer ferroelectric material 34 is elevationally outward of innerconductive material 32 and extends along channel top 20. Any suitableexisting or yet-to-be-developed ferroelectric material may be used.Examples include ferroelectrics that have one or more of transitionmetal oxide, zirconium, zirconium oxide, hafnium, hafnium oxide, leadzirconium titanate, and barium strontium titanate, and may have dopanttherein which comprises one or more of silicon, aluminum, lanthanum,yttrium, erbium, calcium, magnesium, strontium, and a rare earthelement. Two specific examples are Hf_(x)Si_(y)O_(z) andHf_(x)Zr_(y)O_(z). An example thickness for outer ferroelectric material34 is about 10 to 100 Angstroms.

Outer conductive material 36 is elevationally outward of outerferroelectric material 34 and extends along channel top 20. Examplematerials include any of those described above with respect to innerconductive material 32, with one example being a composite of elementaltungsten and TiN. An example thickness for material 32 is about 100 to1,000 Angstroms. Example gate construction 28 may be considered bypeople of skill in the art as MFMIS construction.

In one embodiment, no portion of outer ferroelectric material 34 islaterally over any of channel sidewalls 16, 18, for example as is shown.In one embodiment, no portion of outer conductive material 36 islaterally over any of channel sidewalls 16, 18, for example as shown. Inone embodiment, each source/drain region 22 has a maximum elevationalthickness T_(SD) (FIGS. 1 and 3) that is less than a maximum elevationalthickness T_(ID) of inner dielectric 30 (FIG. 2). In one embodiment,each source/drain region 22 has a maximum elevational thickness T_(SD)that is less than a maximum elevational thickness T_(ICM) of innerconductive material 32 (FIG. 2). In one embodiment, inner conductivematerial 32 has a maximum elevational thickness T_(ICM) that is greaterthan a minimum width C_(MW) of channel 14 taken orthogonally relative toa shortest straight-line distance C_(L) (i.e., channel length) betweensource/drain regions 22 (e.g., C_(MW) being shown in FIG. 2 and C_(L)being shown in FIG. 3). C_(L) is shown as being greater than C_(MW),although this could be reversed or C_(L) and C_(MW) could be equal. Inone embodiment, inner conductive material 32 has a maximum elevationalthickness T_(ICM) that is greater than channel length C_(L). In oneembodiment, inner conductive material 32 and inner dielectric 30 haverespective elevationally innermost surfaces 40, 42 (FIG. 2),respectively, that are not elevationally coincident.

Field effect transistor 10 is shown as being horizontally oriented,although vertical orientation or orientations other than vertical orhorizontal may be used. In this document, vertical is a directiongenerally orthogonal to horizontal, with horizontal referring to ageneral direction along a primary surface relative to which a substrateis processed during fabrication. Further, vertical and horizontal asused herein are generally perpendicular directions relative one anotherindependent of orientation of the substrate in three dimensional space.Additionally, elevational, above, and below are with reference to thevertical direction. Further in the context of this document, avertically oriented transistor is characterized by predominant currentflow through the channel in the vertical direction. A horizontallyoriented transistor is characterized by predominant current flow throughthe channel in the horizontal direction.

In the example embodiments of FIGS. 1-3, each of outer conductivematerial 36, outer ferroelectric material 34, inner conductive material32, and inner dielectric 30 elevationally outward of channel 14 arefour-sided and shown as having vertical sidewalls (i.e., within 5° ofvertical). Other than vertical and/or four-sided structuring may beused, for example more or less than four sides and/or with one or moresides being curved or having a combination of straight and curvedsegments. Example gate construction 28 in FIGS. 2 and 3 is shown ascomprising outer conductive material 36 having four vertical sidewalls45-48, outer ferroelectric material 34 having four vertical sidewalls49-52, inner conductive material 32 having four vertical sidewalls53-56, and inner dielectric 30 having four vertical sidewalls 57-60. Inone embodiment, all of the outer conductive material, the outerferroelectric material, the inner conductive material, and the innerdielectric have at least two laterally opposing vertical sidewallselevationally outward of the channel that are laterally coincidentrelative one another. For example as shown in FIG. 3, sidewalls 47, 51,55, and 59 are laterally coincident relative one another, and as shownin FIG. 2 sidewalls 48, 52, 56, and 60 are laterally coincident relativeone another.

In one embodiment, all of the outer conductive material, the outerferroelectric material, and the inner semiconductive material have atleast two pairs of laterally opposing vertical sidewalls elevationallyoutward of the channel that are laterally coincident relative oneanother, for example as is shown with respect to gate construction 28 inFIGS. 1-3. Specifically, FIG. 3 illustrates a pair of two laterallyopposing vertical sidewalls 47, 48 for outer conductive material 36, apair of two laterally opposing vertical sidewalls 51, 52 for outerferroelectric material 34, a pair of two laterally opposing verticalsidewalls 55, 56 for inner conductive material 32, and wherein sidewalls47, 51, 55, and 59 are laterally coincident relative one another as aresidewalls 48, 52, 56, and 60. FIG. 2 illustrates another pair oflaterally opposing sidewalls 45, 46 of outer conductive material 36,another pair of laterally opposing vertical sidewalls 49, 50 of outerferroelectric material 34, and another pair of two laterally opposingvertical sidewalls 53, 54 of inner conductive material 32, withsidewalls 45, 49, and 53 being laterally coincident relative one anotherand sidewalls 46, 50, and 54 being laterally coincident relative oneanother.

Each of outer conductive material 36, outer ferroelectric material 34,and inner conductive material 32 in the depicted embodiment may beconsidered as having respective encircling perimeter edges in at leastone respective horizontal cross-section elevationally outward of channel14 (e.g., respective perimeter edges as defined by their respectivesidewalls in at least one horizontal plane). In some embodiments, anytwo or all three of such encircling perimeter edges are everywherelaterally coincident, with all three encircling perimeter being shown asbeing laterally coincident in example gate construction 28 in FIGS. 1-3.

Some embodiments of the invention include a plurality of ferroelectricfield effect transistors arrayed in row lines and column lines, forexample an array 65 as shown in FIGS. 4-6. Like numerals from theabove-described embodiments have been used where appropriate, with someconstruction differences being indicated with different numerals.Example array 65 includes a plurality of ferroelectric field effecttransistors 10 substantially as shown and described above with referenceto FIGS. 1-3. Transistors 10 in array 65 are shown as extending in rowlines 66 and column lines 67. Use of “row” and “column” in this documentis for convenience in distinguishing one series of lines from anotherseries of lines. Accordingly, “row” and “column” are intended to besynonymous with any series of lines independent of function. Regardless,the rows may be straight and/or curved and/or parallel and/or notparallel relative one another, as may be the columns. Further, the rowsand columns may intersect relative one another at 90° or at one or moreother angles. In the depicted example, each of the row lines and columnlines are shown as being individually straight and angling relative oneanother at 90°. Dielectric isolating material (not shown) would likelybe between and among lines 66, 67 but is not shown for clarity. Only tworow lines 66 and two column lines 67 are shown in FIGS. 4-6, as are onlytwo ferroelectric transistors 10 being shown in each line 66 and 67. Anarray would likely have thousands or more transistors of likeconstruction therein, arrayed in thousands or more column and row lines.

In one embodiment, at least one of the outer conductive material and theouter ferroelectric material is discontinuous along both of the rowlines and the column lines between immediately adjacent transistors.FIGS. 4-6 depicts such an example, and additionally wherein both ofouter conductive material 36 and outer ferroelectric material 34 arediscontinuous along both of row lines 66 and column lines 67 betweenimmediately adjacent transistors (i.e., within such respective lines).Conductive contacts (not shown) can be made to the individualsource/drain regions 22, and individual conductive contacts (not shown)can be made to outer conductive material 36 of individual gateconstructions 28. Any other attribute(s) or construction(s) as describedabove may be used.

In one embodiment, the outer conductive material and the outerferroelectric material are discontinuous between immediately adjacenttransistors along one of the collective row lines and the collectivecolumn lines. The conductive material and the outer ferroelectricmaterial are continuous between immediately adjacent transistors alongthe other of the collective row lines and the column lines. An alternatesuch example is shown in FIGS. 7-9 with respect to an array 65 a of aplurality of ferroelectric field effect transistors 10. Like numeralsfrom the above-described embodiments have been used where appropriate,with some construction differences being indicated with the suffix “a”or with different numerals. Discontinuity of outer conductive material36 and outer ferroelectric material 34 is shown in array 65 a as beingbetween immediately adjacent transistors 10 along column lines 67. Outerconductive material 36 and outer ferroelectric material 34 arecontinuous between immediately adjacent transistors along row lines 66in the construction of FIGS. 7-9. Of course, the relationship could bereversed (not shown) wherein such materials are continuous along thecolumn lines and discontinuous along the row lines. A chosen arrayconstruction like 65 or 65 a might likely be dependent upon a particularcircuitry architecture being fabricated (e.g., AND vs. NOR). Any otherattribute(s) or construction(s) as described above may be used.

The above array embodiments show a single source/drain region 22 beingshared between and by two immediately adjacent transistors 10 in a givencolumn 67, and semiconductive material 12 also being continuous along anindividual column 67. Alternately, as examples, the semiconductivematerial along individual columns may be formed to be partially orwholly discontinuous between immediately adjacent transistors, and/orsource/drain regions 22 might not be shared by immediately adjacenttransistors. One such example embodiment array 65 b is shown in FIG. 10in comparison to the construction(s) as shown by FIGS. 6 and 9. Likenumerals from the above-described embodiments have been used whereappropriate, with some construction differences being indicated withdifferent numerals or with the suffix “b” or with different numerals. InFIG. 10, dielectric material 70 (e.g., silicon dioxide and/or siliconnitride) may be used to electrically isolate between adjacentcomponents. Dielectric 70 is shown extending through rails 25 and intobase 26. Alternately, the dielectric may extend only partially intorails 25 (not shown) or terminate at the interface of rails 25 and base26 (not shown). Any other attribute(s) or construction(s) as describedabove may be used.

Ferroelectric field effect transistors and arrays in accordance with theinvention may be fabricated using any existing or yet-to-be-developedtechniques, including for example those described below.

Embodiments of the invention include methods of forming a plurality offerroelectric field effect transistors. Example such embodiments aredescribed with reference to FIGS. 11-21. Like numerals from theabove-described embodiments have been used where appropriate, with someconstruction differences being indicated with different numerals or withthe suffix “c”. Referring to FIG. 11, a plurality of trenches 79 hasbeen formed into semiconductive material 12, thereby forming fins orrails 25. Example trenches 79 are shown as being parallel andlongitudinally elongated relative to horizontal.

Referring to FIG. 12-14, inner dielectric 30 has been formed oversidewalls of trenches 79 and over semiconductive material 12 that isbetween trenches 79. Inner dielectric 30 may also be formedelevationally over the bases of trenches 79 as shown. First innerconductive material 31 has been formed over inner dielectric 30, thetrench bases, the trench sidewalls, and semiconductive material 12 thatis between trenches 79. FIGS. 12-14 depict an example embodiment whereinfirst inner conductive material 31 is formed to be both a) continuousbetween trenches 79 in a direction orthogonal to the horizontallongitudinal running direction of parallel trenches 79, and b)continuous within trenches 79. Example techniques for depositing firstinner conductive material include chemical vapor deposition and atomiclayer deposition. Additionally, second inner conductive material 33 chas been formed over and is electrically coupled to first innerconductive material 31. Second inner conductive material 33 c is formedto be elevationally thicker over the semiconductive material that isbetween the trenches than any that is formed elevationally centrallyover the trench bases. In one embodiment and as shown, forming of secondinner conductive material 33 c does form such material over the trenchbases. In one such embodiment, second inner conductive material 33 isformed to run continuously over the trench bases, the trench sidewalls,and semiconductive material 12 between trenches 79 at least in thedirection orthogonal to the longitudinal running direction of paralleltrenches 79. An example technique for depositing second inner conductivematerial 33 c (e.g., TiN) to be elevationally thicker between thetrenches than any that is formed centrally over the trench bases (e.g.,low conformality) includes physical vapor deposition.

Referring to FIGS. 15-17, etching has been conducted at least throughsecond inner conductive material 33 c and first inner conductivematerial 31 to form lines 66 at least of first inner conductive material31 and that run orthogonal to the longitudinal running direction ofparallel trenches 79. Dielectric 30 may also be etched, for examplecompletely there-through as shown.

Referring to FIGS. 18 and 19, such respectively correspond to sectionviews 16 and 17 at a subsequent processing step. Anisotropic etching hasbeen conducted of both a) first inner conductive material 31 from overthe trench bases to isolate first inner conductive material 31 frombeing continuous over the individual trench bases, and b) second innerconductive material 33 c (designated as 33 post-etch) that iselevationally over semiconductive material 12 that is between trenches79. Such anisotropic etching includes at least one etching step which iscommon to the etching of both first inner conductive material 31 andsecond inner conductive material 33 c. In one embodiment and as shown,the etching leaves some of second inner conductive material 33elevationally over first inner conductive material 31 between trenches79, and in one embodiment leaves some of second inner conductivematerial 33 laterally along the trench sidewalls. In one embodimentwhere second inner conductive material 33 c also deposits centrally overthe trench bases, the common etching step also etches it from over thetrench bases to isolate it from being continuous over the individualtrench bases, as is shown. Source/drain regions 22 (FIG. 19) may also beformed.

In the above example embodiment, etching is shown as having occurredfirst with respect to FIGS. 15-17 and then with respect to FIGS. 18 and19. Alternately, this could be reversed whereby the FIGS. 18 and 19etching occurs first (e.g., with respect to the FIGS. 12-14construction) followed by the FIGS. 15-17 etching. Regardless, in oneembodiment, the anisotropic etching exemplified by FIGS. 18 and 19 maybe conducted in the absence of masking (i.e., in maskless/no maskmanner) at least within an entirely of an array region of thetransistors being formed.

Referring to FIGS. 20 and 21, and in one embodiment, dielectric fillmaterial 82 (e.g., silicon dioxide and/or silicon nitride) has beenformed within trenches 79 over the trench bases and at least over firstinner conductive material 31 that is along the trench sidewalls. Outerferroelectric material 34 has been formed elevationally over first innerconductive material 31 that is over semiconductive material 12 that isbetween trenches 79. Additionally, outer conductive material 36 has beenformed elevationally over outer ferroelectric material 34. Outerconductive material 36 and outer ferroelectric material 34 may then bepatterned, by way of example, to produce either the array construction65 of FIGS. 4-6 or the array construction 65 a of FIGS. 7-9.

Any other attribute(s) or construction(s) as described above may beused.

CONCLUSION

In some embodiments, a ferroelectric field effect transistor comprises asemiconductive channel comprising opposing sidewalls and anelevationally outermost top. A source/drain region is at opposite endsof the channel. A gate construction of the transistor comprises innerdielectric extending along the channel top and laterally along thechannel sidewalls. Inner conductive material is elevationally andlaterally outward of the inner dielectric and extends along the channeltop and laterally along the channel sidewalls. Outer ferroelectricmaterial is elevationally outward of the inner conductive material andextends along the channel top. Outer conductive material iselevationally outward of the outer ferroelectric material and extendsalong the channel.

In some embodiments, a plurality of ferroelectric field effecttransistors is arrayed in row lines and column lines. Individual of theferroelectric field effect transistors comprise a semiconductive channelcomprising opposing sidewalls and an elevationally outermost top. Asource/drain region is at opposite ends of the channel. A gateconstruction of the individual transistors comprises inner dielectricextending along the channel top and laterally along the channelsidewalls. Inner conductive material is elevationally and laterallyoutward of the inner dielectric and extends along the channel top andlaterally along the channel sidewalls. Outer ferroelectric material iselevationally outward of the inner conductive material and extends alongthe channel top. Outer conductive material is elevationally outward ofthe outer ferroelectric material and extends along the channel top. Atleast one of the outer conductive material and the outer ferroelectricmaterial is discontinuous along both of the row lines and the columnlines between immediately adjacent transistors.

In some embodiments, a plurality of ferroelectric field effecttransistors arrayed in row lines and column lines comprises individualferroelectric field effect transistors comprise a semiconductive channelcomprising sidewalls and an elevationally outermost top. A source/drainregion is at opposite ends of the channel. A gate construction of theindividual transistors comprises inner dielectric extending along thechannel top and laterally along the channel sidewalls. Inner conductivematerial is elevationally and laterally outward of the inner dielectricand extends along the channel top and laterally along the channelsidewalls. Outer ferroelectric material is elevationally outward of theinner conductive material and extends along the channel top. Outerconductive material is elevationally outward of the outer ferroelectricmaterial and extends along the channel top. The outer conductivematerial and the outer ferroelectric material are discontinuous betweenimmediately adjacent transistors along one of a) the collective rowlines, and b) the collective column lines. The outer conductive materialand the ferroelectric material are continuous between immediatelyadjacent transistors along the other of the collective row lines and thecollective column lines.

In some embodiments, an MFMIS transistor has F along a horizontalchannel surface and I along a vertical channel surface. In some suchembodiments, F is not along any vertical channel surface of thetransistor. In some such embodiments, I is along two vertical channelsurfaces of the transistor. In some such embodiments, total area of Ithat is over the channel of the transistor is greater than total area ofF that is over the channel of the transistor.

In some embodiments, a method of forming a plurality of ferroelectricfield effect transistors comprises forming a plurality of trenches intosemiconductive material, the trenches being parallel and longitudinallyelongated relative to horizontal. Inner dielectric is formed oversidewalls of the trenches and over semiconductive material that isbetween the trenches. First inner conductive material is formed over theinner dielectric, bases of the trenches, the trench sidewalls, and thesemiconductive material that is between the trenches. The first innerconductive material is continuous within and between the trenches atleast in a direction orthogonal to a horizontal longitudinal runningdirection of the parallel trenches. Second inner conductive material isformed over and electrically couples to the first inner conductivematerial. The second inner conductive material is formed elevationallythicker over the semiconductive material that is between the trenchesthan any that is formed elevationally centrally over the trench bases.In at least one common etching step, anisotropically etching isconducted of both: a) the first inner conductive material from over thetrench bases to isolate the first inner conductive material from beingcontinuous over the individual trench bases; and b) the second innerconductive material that is elevationally over the semiconductivematerial that is between the trenches. After the etching, outerferroelectric material is formed elevationally over the first innerconductive material that is over the semiconductive material that isbetween the trenches. Outer conductive material is formed elevationallyover the outer ferroelectric material. Source/drain regions are formedin the semiconductive material that is between the trenches on opposingsides of the first inner conductive material that overlies thesemiconductive material that is between the trenches.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

1-22. (canceled)
 23. A method of forming a plurality of ferroelectricfield effect transistors, comprising: forming a plurality of trenchesinto semiconductive material, the trenches being parallel andlongitudinally elongated relative to horizontal; forming innerdielectric over sidewalls of the trenches and over semiconductivematerial that is between the trenches; forming first inner conductivematerial over the inner dielectric, bases of the trenches, the trenchsidewalls, and the semiconductive material that is between the trenches,the first inner conductive material being continuous within and betweenthe trenches at least in a direction orthogonal to a horizontallongitudinal running direction of the parallel trenches; forming secondinner conductive material over and electrically coupled to the firstinner conductive material; the second inner conductive material beingformed elevationally thicker over the semiconductive material that isbetween the trenches than any that is formed elevationally centrallyover the trench bases; in at least one common etching step,anisotropically etching both: a) the first inner conductive materialfrom over the trench bases to isolate the first inner conductivematerial from being continuous over the individual trench bases; and b)the second inner conductive material that is elevationally over thesemiconductive material that is between the trenches; after the etching,forming outer ferroelectric material elevationally over the first innerconductive material that is over the semiconductive material that isbetween the trenches; forming outer conductive material elevationallyover the outer ferroelectric material; and forming source/drain regionsin the semiconductive material that is between the trenches on opposingsides of the first inner conductive material that overlies thesemiconductive material that is between the trenches.
 24. The method ofclaim 23 wherein said forming inner dielectric also forms the innerdielectric elevationally over the trench bases, said forming first innerconductive material also forms the first inner conductive materialelevationally over the inner dielectric that is over the trench bases,said common etching step exposing the inner dielectric that is over thetrench bases.
 25. The method of claim 23 wherein said forming secondinner conductive material forms the second inner conductive materialelevationally over the trench bases.
 26. The method of claim 23 wherein,said forming first inner conductive material is also continuous withinand between the trenches in the horizontal longitudinal runningdirection of the parallel trenches; and comprising: etching through thefirst inner conductive material within and between the trenches to formlines of the first inner conductive material that run orthogonal to thelongitudinal running direction of the parallel trenches.
 27. The methodof claim 23 wherein said at least one common etching step leaves some ofthe second inner conductive material elevationally over the first innerconductive material between the trenches.
 28. The method of claim 23wherein said forming second inner conductive material also forms thesecond inner conductive material to run continuously over thesemiconductive material between the trenches at least in a directionparallel to the longitudinal running direction of the parallel trenches.29. The method of claim 28 comprising etching through both of the firstinner conductive material and the second inner conductive material toisolate the first inner conductive material and the second innerconductive material from being continuous over the semiconductivematerial between the trenches.
 30. The method of claim 29 wherein saidetching through both of the first inner conductive material and thesecond inner conductive material occurs before said at least one commonetching step.
 31. The method of claim 29 wherein said etching throughboth of the first inner conductive material and the second innerconductive material occurs after said at least one common etching step.32. The method of claim 23 wherein said forming second inner conductivematerial also forms the second inner conductive material to runcontinuously over the trench bases, the trench sidewalls, and thesemiconductive material between the trenches at least in the directionorthogonal to the longitudinal running direction of the paralleltrenches.
 33. The method of claim 32 wherein said at least one commonetching step leaves some of the second inner conductive materiallaterally along the trench sidewalls.
 34. The method of claim 33 whereinsaid at least one common etching step leaves some of the second innerconductive material elevationally over the first inner conductivematerial between the trenches.
 35. The method of claim 23 comprisingforming dielectric fill material within the trenches over the trenchbases and over the first inner conductive material that is along thetrench sidewalls before said forming outer ferroelectric material. 36.The method of claim 23 wherein said anisotropic common etching isconducted in the absence of masking at least within an entirely of anarray region of the transistors being formed.